Prepare the filling: fry the potatoes in heated vegetable oil for a few minutes. Add the onion, garlic and fry for 3 minutes.
Add the mince in small portions and fry until golden. Salt, pepper and add butter.
Prepare the base: beat eggs with sugar until smooth. Add kefir, vegetable oil and mix well.
Pour the resulting mass into the flour sifted with baking powder and salt. Beat well with a whisk until smooth.
Place the filling on the bottom of the pan and pour in the dough, distributing it evenly.
Bake in an oven preheated to 180°C for 30 minutes.
Cut the finished pie into portions and serve.